Presentation on theme: "20th July 2002 Chevron UK full surface tank fire. Fire believed to be started by lightning, the Shell lastfire report also lists lightning as the single."— Presentation transcript:
20th July 2002 Chevron UK full surface tank fire. Fire believed to be started by lightning, the Shell lastfire report also lists lightning as the single greatest cause of floating roof tank fires. Usually, initially limited to rim seal area but can escalate in the following instances Leaking pontoons Sinking roof due to fire water or rain (roof drains closed) Not addressing the rim seal fire quickly enough Tank Contents unknown from information received, or how extinguishment was achieved, Transfer of contents? Foam application? Burned out (no more fuel)?
Obvious concerns over a boil over or tank rupture, all personnel pulled way back. They have not got 360 degree cooling, if only one side is cooled the tank will start to lean. If 360 degree cooling can't be maintained you should consider not cooling We assume that the level in the tank is around the 50% mark, the bottom area is currently unaffected, the top half is peeling down. We would want to remove water from the bottom of the tank to prevent a boil over, a good reason to keep tanks de-watered at all times. Is it an operational instruction to open suction valves on the tank as soon as a fire is reported? Control procedures i.e. pump out the contents and cooling the immediate area. (However if the suction valves were not open would we commit personnel to open them to allow pumping to start - perhaps not at this stage of the fire, but maybe if we caught it early). These comments are from the original sender please discuss as appropriate.
Note: Good separation of tanks, no cooling evident perhaps due to the boil over concerns. Bottom 30% of tank looks pristine (due to contents level?).
Cooling appears ineffectual and may be the reason for the partial collapse, current philosophy is to cool adjacent tanks if required (only if thermal footprint greater than 12.5 Kw/M 2 ) but not to cool the affected tank.
We would have to consider adjacent tank involvement due to our tank proximity's, escalation measures could be to foam the adjacent tank rim seal area (via pourers), cool adjacent tank with monitors. We have proposed the installation of 2 X 4000 litre/minute hard piped monitors on top of the separation bunds to throw up a thermal barrier between tanks.